An international hunting organisation has suspending the membership of the US hunter accused of illegally killing a protected lion in Zimbabwe.

Safari Club International, which promotes big-game hunting worldwide, issued a statement saying memberships for Walter Palmer and his guide in Zimbabwe, Theo Bronkhorst, will be on hiatus until investigations into the lion's death are complete.

Bronkhorst is facing criminal charges in Zimbabwe over the July 1 killing of the beloved lion named Cecil, who was drawn away from a wildlife preserve and shot by Palmer with a bow and arrow. Palmer has said he believed the hunt was legal.

The Safari Club said "those who intentionally take wildlife illegally should be prosecuted and punished to the maximum extent allowed by law".

Palmer, who is a dentist in the US, advised his patients to seek care elsewhere as he remained in hiding amid protests at his clinic.

He said he rarely discussed his big-game hunting because it can be a "divisive and emotionally charged topic".

The-55-year-old has faced protests at his clinic in Bloomington, a suburb of Minneapolis, Minnesota, where he offers general and cosmetic dentistry, as well as intense condemnation online. He has not appeared in public since being identified on Tuesday as a party to the lion's death.

He is an active big-game hunter, with many kills to his name, some of them registered with hunting clubs.

The North Dakota native "enjoys all outdoor activities", according to the biography page on his now-dark clinic website. "Anything allowing him to stay active and observe and photograph wildlife is where you will find Dr Palmer when he not in the office."

Meanwhile in Zimbabwe, a hunting guide and a farm owner appeared in court accused of helping Palmer kill Cecil.

The head of Zimbabwe's safari association said the big cat with the black mane was lured into the kill zone and denied "a chance of a fair chase".

The Zimbabwean men were accused of aiding Palmer, who reportedly paid £32,000 to track and kill a lion.

The dentist referenced the situation in a note to his patients. "I understand and respect that not everyone shares the same views on hunting," he said in the letter, obtained by the local Fox television affiliate KMSP.

The married father of two was the subject of a 2009 New York Times article about big-game hunting in which he said he learned to shoot at the age of five. The article said Palmer had a reputation for being capable of "skewering a playing card from 100 yards" with a compound bow and having "a purist's reputation for his disinclination to carry firearms as back-up".

During the night-time hunt, the Zimbabwean men tied a dead animal to their car to draw the lion out of a national park, said Johnny Rodrigues, chairman of the Zimbabwe Conservation Task Force.

The American is believed to have shot the lion with a crossbow. The wounded cat was then tracked for 40 hours before Palmer fatally shot him with a gun, Mr Rodrigues said.

A professional hunter, Theo Bronkhorst, was accused of failing to "prevent an unlawful hunt". Court documents said he was supervising while Palmer shot the animal.

Bronkhorst was released on £640 bail after appearing in court in Hwange, about 435 miles west of the capital Harare. If convicted he faces up to 15 years in prison.

A second man, farm owner Honest Trymore Ndlovu, also appeared in court but was not charged and released from custody, his lawyer said.

The court documents made no mention of Palmer as a suspect.

Using bait to lure the lion is deemed unethical by the Safari Operators Association of Zimbabwe, of which Bronkhorst is a member. The association has since revoked his licence.

"Ethics are certainly against baiting. Animals are supposed to be given a chance of a fair chase," Emmanuel Fundira, the association's president, said. "In fact, it was not a hunt at all. The animal was baited, and that is not how we do it. It is not allowed."

It was not entirely clear whether baiting is allowed by Zimbabwe law. Mr Fundira said the practice was both unethical and illegal. The conservation group Lion Aid says it is unethical but not expressly forbidden.